Electric burglar-alarm



(No Model.)

J. P. HANSON & J. P. CHRISTENSEN. ELECTRIC BURGLAR ALARM.

N0.-292,806. Patented Feb. 5, 1884.

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UNITED STATES ATENT OEEicE.

JAMES P. HANSON AND JAMES P. CHRISTENSEN, OF CHICAGO, ILLINOIS.

ELECTRIC BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 292,806, dated February 5, 1884.

Application filed May 10, 1883. (No model.)

To aZZ whom, it may concern Be it known that we, JAMES P. Hanson and JAMES P. CHRISTENSEN, citizens of the the United States of America, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Electric Burglar-Alarms, of which the following is specification, reference being had therein to the accompanying drawings.

This invention relates to electric appliances in stores that will announce the presence of burglars; and it is our object to produce an apparatus that when placed behind a showwindow or inside of a show-case will announce the breaking of a glass or the removing of an article by burglars.

Our invention therefore consists of the novel devices and combinations of devices hereinafter described and specifically claimed.

In the drawings, Figure 1 represents a side elevation, and Fig. 2 aplan view, of the apparatus.

Corresponding letters in the several figures of the drawings designate like parts.

base of the apparatus, and is provided with four corner-feet, a. Upon this plate are secured two posts, B B, one at each side, and both in line with each other, that are grooved in their top end to form bearings for the knife edged ends of a shaft, 7). Upon the center of this shaft 1) is mounted a vibratable metallic beam, C, the rearward rounded extension of which carries a balance-weight, D, that is adjustably secured thereon by a set-screw, 0. Upon its front end the beam C supports an oblong shelf, E, that is shaped to be rearwardly-inciined, and has a front upwardly bent flange. This shelf E is reenforced by a bar, 6, that is secured under its horizontal portion, and has a pin, f, which enters a hole in beam C, and is removably secured therein by a set-screw, g.

F and G are contact-posts secured upon plate A, under and in line with beam C, and at equal distance from the center of shaft Z). Post F is just below pin f of shelf E, the end of which pin forms the contact-point with post F. Just above the center of post G the beam C is tapped for a set-screw, j, the end of which forms the contact-point with post G. Posts H and I are secured upon the rear corners of plate A, and have each a screw for connecting the end of circuit-wire, h and 'i. The posts F, G, and I are insulated from plate A each by a rubber washer, m and post F, as well as post G, are both connected with post I by insulated wires a and 0 below plate A. Upon shelf E are placed articles to be exhibited that are on sale, (as in Fig. 1 we have represented a watch placed thereon,) and the thus loaded shelf E is to be counterbalanced in the manner of a weighing-scale by the adjustment of weight D, that both points f and j of beam C will be clear off the posts F and G, when the electric circuit will be incomplete, but that the least weight added upon shclfE will throw thebeam C out of balance, and will bring pointf in contact with post F, or with removing the small est article from shelf E the point of screw j will be brought in Contact with post G,

when in either case the electric circuit will be completed and the alarm-bell will ring.

This apparatus being placed behind a showwindow or inside of a show-case, and a burglar breaking the glass for getting to the articles, the smallest piece of glass that may drop on shelf E will start the alarm-bell, and the A denotes a metallic plate that forms the l same will take place when a burglar first picks the lock and then begins to remove an article from the shelf E.

This device, as will be seen, is very simple in its construction, and is reliable and practi cable in its operation.

What we claim is 1. In a burglar-alarm, the balance-beam C, carrying shelf E, and having counter-weight D, in combination with contactposts F and G, both connected with one of the poles of an incomplete electric circuit, all substantially as described, to operate as specified.

2. In aburglar-alarm, the balancebeam C, with shelf E and counter weight D, and mounted upon shaft 1), pivoted on posts B B of plate A, in combination with contact-posts F and G and circuitwire connecting posts H and I, all constructed and arranged to operate substantially as and for the purpose set forth.

In testimony whereof we affix our signatures in presence of two witnesses.

JAMES P. HANSON. JAMES P. CHRISTENSEN.

\Vitnesses:

ADAM. GEO. WHITE, R. G. ScnmD. 

